Johansson, 27, said she wanted to be known for her actress prowess, reported Daily Express.
"I never wanted to be a sex symbol, I wanted to be a character actor. But I think women who are curvy can be pigeonholed in that bombshell thing. What can I do about it?
"I'm never going to be rail-thin. Everyone in Hollywood is so damn skinny and you constantly feel like you're not skinny enough," she said.
Johansson, who was seen flexing her muscles as the Black Widow in "Iron Man 2", said she had to watch her calorie intake a little closer for the superhero flick.
"You're training and doing all that stunt work so you eat a lot of green things. I spent a lot of time in the gym because of all these huge choreographed fight scenes, and I was happy to do that," she said.